The present invention relates generally to automotive vehicle occupant restraint systems, particularly air bags. It relates more specifically to mechanisms for selectively modifying the deployment of such systems.
Inflatable occupant restraint, or air bag, systems have come into widespread use in the automotive industry. Although these devices have proved to be very successful in reducing the secondary collision between a vehicle occupant and the interior of the vehicle in the event of an accident, there are certain instances in which it is desirable to reduce the inflation power or disable operation of an air bag system. One such instance occurs when the occupant is seated in a rear facing infant seat (RFIS), because the air bag can (and has) injure or kill such occupants by slamming the RFIS toward the rear of the vehicle. Another instance occurs when the passenger weighs less than 66 pounds, because such passengers are especially vulnerable to the high impact force of the air bag. Also, occupants who are for some reason near the air bag, such as short vehicle operators, can be powerfully impacted by an inflating air bag. Finally, it is undesirable to deploy the air bag when the passenger seat is empty, because the replacement cost of an air bag is on the order of $700.
To overcome these problems, various techniques have been suggested to selectively disable the air bag. The simplest of these techniques, an operator-controlled switch to selectively disconnect the electrical circuitry to the air bag, is not considered to be a preferred solution because it is dependent upon user input to ensure that the switch is in the proper orientation dependent upon the situation. Accordingly, the desired objective is to automatically reduce the inflation power or totally disable the inflation of the air bag depending on the weight, size, and position of the occupant, as well as to disable deployment when the occupant is in a RFIS or when the seat is empty.
U.S. Pat. No. 5,570,903 of Meister et al. discloses a system utilizing a weight sensor in the seat and magnetic or optical sensors which communicate with corresponding devices mounted on a RFIS. One disadvantage of this system is the requirement that a special RFIS be used with the system. Another disadvantage that has been discovered with systems using weight sensors is that the weight detected by the sensor changes as the occupant moves in the seat. Thus weight sensors are not considered in the industry to be a reliable indicator for activation of an air bag.